GRINDR, a gay-specific smart-phone social-networking application (or "app") used by gays to find sex partners also proved useful as a recruiting tool for an HIV risk survey in Los Angeles [1]. Most study participants had an HIV test in the past year, following CDC guidelines. Findings also suggested these men are not serosorting (having sex only with men of the same HIV status).

Young gay men still account for the largest proportion of new HIV infections in the United States. Many young gays are technologically savvy and use global positioning satellite (GPS)-based social networking apps like GRINDR to find sex partners. Over 1.5 million men use GRINDR, and about 8000 are downloading the app every day. More than 46,500 Los Angeles gays use GRINDR.

Researchers at the University of California, Los Angeles (UCLA) planned this study to see if they could recruit young gays for an HIV risk survey using GRINDR and to determine what kind of population GRINDR would gather. Any GRINDR users 18 to 29 years old were eligible.

Recruitment was not easy, despite the offer of a $25 iTunes gift card. The UCLA team contacted 4808 men to enroll 375 (7.8%) over 5 months. Only 219 of those men (4.5%) were recruited via GRINDR chats. Enrollees completed a computer survey at field sites (not online). At the time of the study, GRINDR was available only for iPhones, not for other platforms.

The study group had a median age of 25 (interquartile range [IQR] 22 to 27), 43% were white, 34% Latino, and 6% black. Median annual income stood at $25,000 (IQR $15,100 to $39,600). Most men (312 or 83%) had been tested for HIV in the last year, in accordance with CDC advice that people with a high HIV risk get tested once a year. Sixteen men (4%) had never been tested for HIV. Sixteen men reported that they had HIV infection.

Almost all men (369 or 98%) said they had sex with men in the last year, while 37 (10%) also had sex with women, and 3 had sex with transgender women or men. Study participants had a median of 4 sex partners in the last year, 2 in the last 3 months, and 1 in the last month. While 153 men (43%) reported unprotected receptive anal intercourse in the past month, 163 (47%) reported unprotected insertive anal intercourse. Almost half of the study group (181 or 48%) had sex while under the influence of alcohol or drugs.

Substantial proportions of study respondents reported a history of gonorrhea (17.9%), Chlamydia (13.6%), or syphilis (9.1%). These men reported averages of 1.9 anal sex partners in the last month, 3.8 in the last 3 months, and 10 in the last year.

More than half of the study group (210 men or 56%) found a sex partner via GRINDR. When using GRINDR, fewer HIV-positive than HIV-negative men asked their potential partner's HIV status, a finding suggesting that serosorting is not highly prevalent in this population.

The seemingly startling bookstore association reflects the gay cruising scene in the LA area frequented by most study participants: There is only one bookstore and gay men often use it to find sex partners.

This analysis also found a trend toward lower risk of self-reported HIV infection among men who said their GRINDR use included finding friends (AOR 0.17, 95% confidence interval 0.03 to 1.06, P = 0.09).

The UCLA team concluded that GRINDR is "a feasible and acceptable method" to recruit young gay men for this kind of research. Because HIV prevalence in this study group was similar to prevalence in young gays recruited by other techniques, the researchers believe GRINDR-based recruitment does not lead to sample-selection bias.

The investigators noted that high rates of sexually transmitted infections and risk behaviors in these men indicate that they run a high risk of HIV infection.